1. Field of the Invention
The present invention relates to a light timing controlling method and device for an AC_LED, and more particularly, to a method and device for controlling light timing of an AC_LED by multiphase voltage sources.
2. Description of the Prior Art
FIGS. 1A to 1D show a traditional AC_LED driven by a single-phase voltage source.
FIG. 1A shows a traditional controlling system for an AC_LED. A traditional AC_LED 10 is electrically coupling to a single-phase voltage source, for example, a nominal voltage of AC 110V. The AC_LED used in this invention is triggered by 90V as an example. An AC_LED 10 is composed of two DC_LEDs being electrically coupling with each other in electrically reverse direction. FIG. 1A shows that two DC_LEDs are arranged in a reversed direction, so that the two DC_LEDs are connected head to tail with shortest metal wires. The positive terminal of the first DC_LED (positive DC_LED) is connected to the negative terminal of the second DC_LED (negative DC_LED), and the negative terminal of the first DC_LED is connected to the positive terminal of the second DC_LED. The AC_LED 10 turns on when the supplied voltage reaches the trigger voltage, for example, 90V as exemplified in the invention. The first or positive DC_LED turns on when the voltage is above +90V, and turns off when the voltage falls down below 90V, The second or negative DC_LED turns on when the voltage is below −90V and the negative DC_LED turns off when the voltage rises above −90V.
FIG. 1B shows a traditional voltage waveform disclosed in the prior art. The abscissa shows a voltage phase with a scale of 0˜360 degree. The ordinate shows voltage with a scale of −200V˜+200V. The nominal 110V is a root-mean-square (RMS) of actual voltage supplied. In other words, a nominal 110V power source actually fluctuates in between −156V˜+156V. The voltage peak (Vp) is calculated as follows:Vp=1.414×RMS=1.414×110V=156V
FIG. 1B shows a sine waveform of a nominal 110V power source, disclosing a voltage of 0V at phase 0 degree, a positive voltage peak of +156V at phase 90 degree, a voltage of 0V at phase 180 degree, a negative voltage peak of −156V at phase 270 degree, and a voltage of 0V at phase 360 degree.
FIG. 1C shows a traditional current waveform disclosed in the prior art. The abscissa shows a voltage phase with a scale of 0˜360 degree. The ordinate shows current with a scale of −6.0 mA˜+6.0 mA. The traditional current waveform of FIG. 1C indicates a current of 0 mA at phase 0˜30 degree with voltage higher than 90V at phase higher than 30 degree where the positive DC_LED is triggered to turn on, a positive current peak of +5.2 mA at phase 90 degree, a current of 0 mA at phase 150˜210 degree where the positive DC_LED is turned off due to voltage falls down below the trigger voltage 90V, and the positive DC_LED is turned on during phase 30˜150 degree and turned off in the remaining period. Conversely, as shown in FIG. 1C, the voltage is lower than 90V at phase 210 degree where the negative DC_LED is triggered to turn on; there is a current peak of +5.2 mA at phase 270 degree; the voltage rises higher than −90V, and the negative DC_LED is turned off. In summary, the positive AC_LED turns on during phase 30˜150 degree and turns off during the remaining period, and the negative DC_LED turns on during phase 210˜330 degree and turned off in the remaining period.
FIG. 1D shows a traditional power waveform disclosed in the prior art. The abscissa shows voltage phase with a scale of 0˜360 degree. The ordinate shows power with a scale of 0.0 W˜1.0 W. The traditional power waveform of FIG. 1D indicates a power of 0 W at phase 0˜30 degree, a power peak of 0.8 W at phase 90 degree, a power of 0 W at phase 150˜210 degree, a power peak of 0.8 W at phase 270 degree, and a power of 0 W at phase 330˜360 degree.
The prior art disclosing single-phase voltage source-based control lacks flexibility in light timing because of its fixed and unchangeable power cycle. The prior art fails to meet the need for a variety of light timing of the AC_LED.